| use super::plumbing::*; |
| use super::*; |
| |
| use std::fmt::{self, Debug}; |
| |
| /// `FlatMap` maps each element to a parallel iterator, then flattens these iterators together. |
| /// This struct is created by the [`flat_map()`] method on [`ParallelIterator`] |
| /// |
| /// [`flat_map()`]: trait.ParallelIterator.html#method.flat_map |
| /// [`ParallelIterator`]: trait.ParallelIterator.html |
| #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] |
| #[derive(Clone)] |
| pub struct FlatMap<I: ParallelIterator, F> { |
| base: I, |
| map_op: F, |
| } |
| |
| impl<I: ParallelIterator + Debug, F> Debug for FlatMap<I, F> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("FlatMap").field("base", &self.base).finish() |
| } |
| } |
| |
| impl<I: ParallelIterator, F> FlatMap<I, F> { |
| /// Creates a new `FlatMap` iterator. |
| pub(super) fn new(base: I, map_op: F) -> Self { |
| FlatMap { base, map_op } |
| } |
| } |
| |
| impl<I, F, PI> ParallelIterator for FlatMap<I, F> |
| where |
| I: ParallelIterator, |
| F: Fn(I::Item) -> PI + Sync + Send, |
| PI: IntoParallelIterator, |
| { |
| type Item = PI::Item; |
| |
| fn drive_unindexed<C>(self, consumer: C) -> C::Result |
| where |
| C: UnindexedConsumer<Self::Item>, |
| { |
| let consumer = FlatMapConsumer::new(consumer, &self.map_op); |
| self.base.drive_unindexed(consumer) |
| } |
| } |
| |
| /// //////////////////////////////////////////////////////////////////////// |
| /// Consumer implementation |
| |
| struct FlatMapConsumer<'f, C, F> { |
| base: C, |
| map_op: &'f F, |
| } |
| |
| impl<'f, C, F> FlatMapConsumer<'f, C, F> { |
| fn new(base: C, map_op: &'f F) -> Self { |
| FlatMapConsumer { base, map_op } |
| } |
| } |
| |
| impl<'f, T, U, C, F> Consumer<T> for FlatMapConsumer<'f, C, F> |
| where |
| C: UnindexedConsumer<U::Item>, |
| F: Fn(T) -> U + Sync, |
| U: IntoParallelIterator, |
| { |
| type Folder = FlatMapFolder<'f, C, F, C::Result>; |
| type Reducer = C::Reducer; |
| type Result = C::Result; |
| |
| fn split_at(self, index: usize) -> (Self, Self, C::Reducer) { |
| let (left, right, reducer) = self.base.split_at(index); |
| ( |
| FlatMapConsumer::new(left, self.map_op), |
| FlatMapConsumer::new(right, self.map_op), |
| reducer, |
| ) |
| } |
| |
| fn into_folder(self) -> Self::Folder { |
| FlatMapFolder { |
| base: self.base, |
| map_op: self.map_op, |
| previous: None, |
| } |
| } |
| |
| fn full(&self) -> bool { |
| self.base.full() |
| } |
| } |
| |
| impl<'f, T, U, C, F> UnindexedConsumer<T> for FlatMapConsumer<'f, C, F> |
| where |
| C: UnindexedConsumer<U::Item>, |
| F: Fn(T) -> U + Sync, |
| U: IntoParallelIterator, |
| { |
| fn split_off_left(&self) -> Self { |
| FlatMapConsumer::new(self.base.split_off_left(), self.map_op) |
| } |
| |
| fn to_reducer(&self) -> Self::Reducer { |
| self.base.to_reducer() |
| } |
| } |
| |
| struct FlatMapFolder<'f, C, F, R> { |
| base: C, |
| map_op: &'f F, |
| previous: Option<R>, |
| } |
| |
| impl<'f, T, U, C, F> Folder<T> for FlatMapFolder<'f, C, F, C::Result> |
| where |
| C: UnindexedConsumer<U::Item>, |
| F: Fn(T) -> U + Sync, |
| U: IntoParallelIterator, |
| { |
| type Result = C::Result; |
| |
| fn consume(self, item: T) -> Self { |
| let map_op = self.map_op; |
| let par_iter = map_op(item).into_par_iter(); |
| let consumer = self.base.split_off_left(); |
| let result = par_iter.drive_unindexed(consumer); |
| |
| let previous = match self.previous { |
| None => Some(result), |
| Some(previous) => { |
| let reducer = self.base.to_reducer(); |
| Some(reducer.reduce(previous, result)) |
| } |
| }; |
| |
| FlatMapFolder { |
| base: self.base, |
| map_op, |
| previous, |
| } |
| } |
| |
| fn complete(self) -> Self::Result { |
| match self.previous { |
| Some(previous) => previous, |
| None => self.base.into_folder().complete(), |
| } |
| } |
| |
| fn full(&self) -> bool { |
| self.base.full() |
| } |
| } |